Diet of the Burrowing Owl Athene cunicularia (Molina, 1782) in a university campus of Southern Brazil

The burrowing owl Athene cunicularia (Molina 1782) is a broadly distributed species, ranging from North America to the southernmost part of South America. It in habits both natural and urban areas, such as grasslands, pastures, and parks. In this study, we aimed to investigate the diet of three pairs of A. cunicularia from the Cedeteg campus of Unicentro University, Paraná, Brazil. Pellets (regurgitated material) from the three nests were sampled every 15 days during six months, from June/2016 to December/2016. The sampled pellets were kept in duly labeled paper bags for about 48 hours, after which food items were sorted and identified to the lowest taxonomic resolution possible. The frequency of occurrence of each food item in relation to the total of pellets sampled (N=86) was calculated. Arthropods (100% frequency of occurrence) and vertebrates (76%) were found in pellets of all three nests. Coleopterans were the most frequent arthropods (100%), whereas mammals were the most frequent vertebrates (57%), which also included birds (9%), amphibians (2%), and pisces (1%). The broad variety of food items found in A. cunicularia diet indicates generalist and opportunistic feeding habits. Although arthropod frequency of occurrence was higher than that of vertebrates, the last may represent a higher energetic gain in terms of biomass. Finally, given that generalist predators tend to feed on the most abundant prey available (i.e. density-dependent foraging), our results evidence the potential importance of A. cunicularia for biological control.